So I am trying to calculate the water temp additions for a step mash for 5 BBL. I essentially want 3 steps, 122F, 152F and 168F. I have a single HLT so I have one temp in the HLT to deal with. Therfore I need to blend cold with HLT water to create my steps. Here are the calculations from Palmer:

http://www.homebrewtalk.com/wiki/index.php/Infusion_mashingI'm trying to create a spreadsheet with the formula's embedded, but not sure why I can't seem to make it work? On this recipe, I'm using 130Kg of grain. Let's say grain temp of 70F. I need to come up with some combination of grain, water/temp additions to make this approach work.

Let's say an initial step of .75 ration or grain to water and then whatever temps and volumes make sense from there.

Just thought I would throw it out there in case we had some bored mathematicians ;-)